The placebo effect in agoraphobia--II.

Analyses in 44 agoraphobic patients given single-blind placebo over a two-week period, without the customary confound of instructions of exposure to phobic situations, replicated previous findings of a weak placebo response in that there were statistically, but not clinically, significant reductions in panic and phobic symptoms. Further analyses of a representative subsample of 10 patients who continued to receive placebo revealed that the placebo response was maintained and even increased at the end of 10 weeks when 20% to 30% of the patients could be classified as marked responders on key panic and phobic measures. Results also revealed an interesting observation that most of the improvement in panic, anxiety, and depression occurred early whereas improvement in phobic measures was more gradual and increased significantly over time. Implications for clinical research are briefly discussed.